Sexual mimicry

Question 1

Cunha 2003

Answer 1

Mimicry of primary sexual characteristics in female spotted hyena: penis-like clitoris, urogenital meatus very elastic, false scrotum from vulval tissue, lack external vagina.
Males = longer and slender penis, angular glans, urogenital meatus not very elastic.

Question 2

Frank 1995

Answer 2

High reproductive cost of giving birth: 60% of first-born cubs die of anoxia as meatus has not torn.

Question 3

Cunha 2005

Answer 3

Masculinisation of F genitalia appears before differentiation of F ovary & adrenal gland.
So if due to androgens, must be different source of androgens.

Question 4

East and Hofer 2002

Answer 4

Link between size, ADs and female aggression does not exist e.g. social rank not linked to size.
Effect of siblicide instead? Neonates very aggressive. Due to competition for milk?

Question 5

Drea 2002

Answer 5

Female hyenas exposed to similar levels of prenatal T as males.

(but then why are Fs much more aggressive?)

Question 6

Shozu 1991

Answer 6

Human placenta deficient in aromatase = child showed masculinised genitals. Could not convert placental T to OE (which would be prevented from entering female foetus), instead T crosses placental barrier and masculinised structures in female.

Question 7

Maternal prenatal androgens

Answer 7

Dominant females produce higher AD levels in 2nd half of pregnancy (negative correlation between social rank and foecal androgens, if highest rank is 1).
And correlates with aggression of cubs when born.
So maternal AD levels affect rank, rank determines reproductive success which creates selective drive for high maternal ADs.

Question 8

Glickman 2006

Answer 8

Neonatal AD blockers don’t block formation of penile clitories, although it is shorter and thicker and not as elastic.
Higher OE levels caused much more elastic meatus. Also increased LH surge in response to GnRH.
Mortality rates decreased to 0!
So cause of high neonatal mortality directly linked to steroid-dependent development of penile clitoris?

Question 9

Drea 2002

Answer 9

Neonatal AD blockers in males = infertile. Penis too small. More female-like.

Females = didn’t

Question 10

Forger 1996

Answer 10

Neonatal AD blockers don’t block formation of penile clitories, although it is shorter and thicker and not as elastic.

Neonatal AD blockers = feminised SNB muscles in males.

And brains still sexually dimorphic! Males 2x larger SDN-POA in hypothalamus. This is despite similar T levels.

Question 11

Glickman 1992

Answer 11

Prepubertal gonadectomy doesn’t affect size or growth of female genitalia.

Question 12

Wells 1956

Answer 12

Pseudohermaphrodite rhesus monkeys = penile clitoris still not like hyenas, hyenas is unique. Not just masculinised, can give birth through it etc.